Drug delivery devices, such as inhalers or injection devices, that can be easily operated by a patient himself are well known in the art. Generally, such devices have trigger mechanisms to actuate drug dispensing.
For instance, there are trigger mechanisms designed as breath-actuation mechanisms in mechanically powered inhalers, such as a dry powder inhaler (DPI), an aqueous droplet inhaler (ADI) and/or a metered dose inhaler (MDI).
US 2004 020486 A1 discloses an inhaler for delivery of medicament from a canister which is compressible to deliver a dose of medicament. The inhaler comprises a housing for holding a canister. The housing having a mouthpiece for inhalation of a dose of medicament delivered by the canister. Furthermore the inhaler includes a breath-actuated actuation mechanism for compressing a canister held in the housing in response to inhalation at the mouthpiece. The actuation mechanism includes a locking mechanism arranged to lock the canister in a compressed state. The locking mechanism has a vane in the form of a flap and being responsive to the inhalation at the mouthpiece to release the canister when the level of inhalation at the mouthpiece falls below a predetermined threshold. It is necessary for the user to take e deep breath to ensure proper inhalation of the medicament so the delay for reset of the canister is sufficient long.
U.S. Pat. No. 6,405,727 B1 discloses a dosing device comprising a dispensing means for dispensing a dose material, a first biasing means for engaging with the dispensing means, and a dose activating mechanism. The dose activating mechanism comprises a deflectable member moveable by airflow, and a series of at least two moveable elements which transmit movement of the first element in the series to the last element in the series by a cascade effect, such that movement of the deflectable member is transferred to the first element of the series and a second biasing means communicates with one the at least two moveable elements. As movement is transferred between the moveable elements, energy stored in the second biasing means is released to increase the force associated with the movement of the moveable elements.
US 2007 118094 A1 discloses a needle-less injector device for delivering a dose of fluid intradermally, subcutaneously or intramuscularly to an animal or human. The device includes an inner housing having opposed ends. A syringe is disposed in one end of the inner housing. The syringe includes a nozzle for delivering a dose of fluid held within the syringe. A plunger is movably disposed within the syringe. A spring-powered hammer is movably disposed within the inner housing. The hammer cooperates with the plunger to drive the dose of medicament from the nozzle. An injection delivery spring for powering the hammer is positioned and compressed between the other vend of the inner housing and the spring powered hammer. An outer housing slideably supports the inner housing. A skin tensioning spring is mounted between the inner housing and the outer housing, the skin tensioning spring biasing the nozzle of the syringe against the animal or human. A trigger mechanism is disposed in the outer housing, the trigger mechanism cooperating with the spring powered hammer to release the injection delivery spring, wherein the size of the injection delivery spring and the length of the hammer dictate the amount of dose delivered and whether the dose is delivered intradermally, subcutaneously or intramuscularly to an animal or human.